libbe(3): promote dependent clones when destroying an environment

[jwmaag_gmail.com]

Summary

When removing a boot environment iterate over the dependents and
process the snapshots by grabbing any clones. Promote the clones we
found and then remove the target environment.

Test Plan

• create a boot environment be0
• create two boot environments from be0 (be1, be2)
• destroy be0
• destroy be1

• create be1 from be0
• create be2 from be1
• create be3 from be2
• destroy be2, be3, be1

[jwmaag_gmail.com]

update comment

[kevans]

Overall approach LGTM.

lib/libbe/be.c

205 ↗

(On Diff #66129)

"promote"

223 ↗

(On Diff #66129)

This initialization should probably be moved down to just before we iterate over the promotelist; once found is set, we're never resetting it back to false.

243 ↗

(On Diff #66129)

space after if

247 ↗

(On Diff #66129)

space after if

272 ↗

(On Diff #66129)

space after while

407 ↗

(On Diff #66129)

space after if, before opening brace.

sbin/bectl/tests/bectl_test.sh

151 ↗

(On Diff #66129)

Unwanted trailing space.

[jwmaag_gmail.com]

fix nits, rearrange promote list unique logic

[kevans]

lib/libbe/be.c

250 ↗

(On Diff #66152)

newentry is leaked here

252 ↗

(On Diff #66152)

We should check return value of strdup here, too, while we're at it.

[jwmaag_gmail.com]

free newentry when following the dup or error path

[jwmaag_gmail.com]

on allocation failures, set err = enomem and break out of the loop so we clean up any nvlists/zfs handles instead of just returning